Alcohols having 3-methyl or 3,5-dimethyl or 3,5-dimethylphenyl groups, a process for their preparation and a fragrance composition containing same

ABSTRACT

2-Methyl-3-(3-methylphenyl)-propan-1-ol, 2-methyl-3-(3,5-dimethylphenyl)-propan-1-ol, 1-(3-methylphenyl)-2-methylbutan-3-ol and 1-(3,5-dimethylphenyl)-2-methylbutan-3-ol, their preparation and use as fragrances.

3-Phenylpropionaldehyde and 3-phenylpropan-1-ol have long been used asfragrances. Furthermore, the fragrant character of propionaldehydes ofthe general formula ##STR1## is disclosed in Japanese PublishedSpecification JP 61,194,045 (CA 106:32752m).

The use of 1,1-di(C₁ -C₆ -alkyl)-2-phenylethane derivatives as perfumesis disclosed in European patent application No. 0 076,493. However, allcompounds described therein exhibit no additional substitution of thephenyl radical, such as is evident, for example, for2,2-dimethyl-3-phenylpropanol in Example 2 of this specification.

It has now been found that new fragrances having a predominantly floralcharacter are formed by methyl substitution in the 3- or 3,5-position ofthe benzyl radical.

The invention relates to 2-methyl-3-(3-methylphenyl)-propan-1-ol,2-methyl-3-(3,5-dimethylphenyl)propan-1-ol,1-(3-methylphenyl)-2-methylbutan-3-ol and1-3,5-dimethylphenyl)-2-methylbutan-3-ol.

A process for the preparation of 2-methyl-3-(3-methylphenyl)-propan-1-oland 2-methyl-3-(3,5-dimethylphenyl)-propan-1-ol comprises

(a) reacting 3-methylbenzaldehyde or 3,5-dimethylbenzaldehyde withpropionaldehyde in the presence of bases and

(b1) hydrogenating the reaction product from (a), or

(a1) reacting 3-methylbenzylmagnesium chloride or3,5-dimethylbenzylmagnesium chloride with chloroacetone and

(b) catalytically hydrogenating the reaction product from (a1) afterbase-catalyzed cyclization.

These reaction pathways are illustrated by the following reactionschemes. ##STR2##

The benzaldehydes, propionaldehyde, benzyl chlorides and chloroacetoneused as starting compounds are known substances. The benzylmagnesiumchlorides can be obtained in a manner known per se from metallicmagnesium and the benzyl chlorides.

The reaction in accordance with (a) is preferably carried out usingalkali metal hydroxides, in particular sodium hydroxide or potassiumhydroxide, at temperatures of preferably -5° C. to 80° C. in polarsolvents such as alcohols, for example methanol or ethanol. The reactionproduct in accordance with (a) is then hydrogenated using reductioncatalysts such as palladium on active carbon or Raney nickel andhydrogen and the alcohol is finally separated by fractionaldistillation.

The reaction in accordance with (a1) is preferably carried out attemperatures from 0° C. to 60° C. in dry inert solvents such as diethylether and/or tetrahydrofuran with subsequent hydrolysis ideally in thepresence of mineral acids such as hydrochloric acid, sulfuric acid andthe like. The reaction product according to (a1) is subsequentlycyclized to the epoxide using bases, preferably alkali metal hydroxidessuch as sodium hydroxide or potassium hydroxide, at temperatures ofpreferably from 0° C. to 50° C., then catalytically hydrogenated,preferably using reduction catalysts such as palladium on active carbonand hydrogen and the alcohol is finally separated by fractionaldistillation.

A further process for the preparation of2-methyl-3-(3-methylphenyl)-propan-1-ol and 2-methyl-3-(3,5-dimethylphenyl)-propan-1-ol comprises

(a2) reacting 3-methylbenzyl chloride or 3,5-dimethylbenzyl chloridewith diethyl methylmalonate,

(b2) thermally decarboxylating the reaction product from (a2) afterhydrolysis and

(c2) hydrogenating the reaction product from (b2) or

(a3) reacting 3-methylbenzaldehyde or 3,5-dimethylbenzaldehyde withmethyl 2-bromopropionate and, after elimination of water,

(b3) hydrogenating the reaction product from (a3).

These reaction pathways are illustrated by the following reactionschemes. ##STR3##

Diethyl methylmalonate and methyl 2-bromopropionate are known compounds.The reaction in accordance with (a2) is preferably carried out attemperatures from 70° to 120° C. in the presence of a base such assodium carbonate or potassium carbonate. After hydrolysis, for exampleusing bases such as sodium hydroxide or potassium hydroxide, the productis thermally decarboxylated, preferably at 120° C. to 150° C. The acidobtained or the esterification product with alcohols such as methanol orethanol is reacted with hydrogenating agents such as lithium aluminumhydride or hydrogen in the presence of a suitable catalyst.

The reaction in accordance with (a3) is preferably carried out attemperatures from 80° C. to 110° C. in the presence of metallic zinc.After elimination of water, the ester obtained is reacted withhydrogenating agents such as lithium aluminum hydride or hydrogen in thepresence of a suitable catalyst.

Processes for the preparation of 1-(3-methylphenyl)-2-methylbutan-3oland 1-(3,5-dimethylphenyl)-2-methylbutan-3-ol comprise reacting2-methyl-3-(3-methylphenyl)-propanol or2-methyl-3-(3,5-dimethylphenyl)propanol with methylmagnesium halide(halogen=Cl, Br, I)

or

reacting 3-methylbenzyl chloride or 3,5-dimethylbenzyl chloride withmethyl ethyl ketone in an organic/alkaline 2-phase system in thepresence of a phase transfer catalyst.

Methyl halides and methyl ethyl ketone are known. The methylmagnesiumhalides can be obtained in a manner known per se from metallic magnesiumand the methyl halides. The reaction of the propanals with themethylmagnesium halide is preferably carried out at temperatures from 0°to 50° C. in dry inert solvents such as diethyl ether and/ortetrahydrofuran with subsequent hydrolysis ideally in the presence ofmineral acids such as hydrochloric acid, sulfuric acid and the like.

In the reaction of benzyl chloride with methyl ethyl ketone, thereactants are employed in approximately equimolar amounts, or methylethyl ketone is employed in excess. The organic/alkaline 2-phase systemis formed from an organic water-immiscible inert solvent and a 5-50%strength by weight aqueous solution of alkali metal hydroxide or alkalimetal hydroxide present in solid form. Examples of alkali metalhydroxides are sodium hydroxide or potassium hydroxide. Phase transfercatalysts which are employed are, for example, crown ethers orquaternary ammonium or phosphonium salts in amounts of 0.5-5 mol-% basedon benzyl chloride.

Regarding further details, reference should be made expressly to theexamples.

The compounds according to the invention are used as fragrances.

The alcohols according to the invention have a very wide area ofapplication on account of their stability to air and liquors. Inaddition to use in perfumery, they are suitable for perfuming detergentsand cleaners, textiles, plastic products and the like.

EXAMPLE 1 2-Methyl-3-(3-methylphenyl)-propan-1-ol

7.5 g of KOH were dissolved in 240 ml of ethanol in a 1 l four-neckedflask with stirring and flushing with argon. First 123 g of3-methylbenzaldehyde, then, in the course of about 4 hours, 62 g ofpropionaldehyde were added with ice cooling. The reaction temperaturewas 8° C. Subsequently, small pieces of ice, softened water and etherwere added to the mixture. The lower layer was discarded, and the upperlayer was washed with 300-400 ml of water and then distilled through a20-cm long column containing 7 mm glass helices. 116 g of2-(3-methylbenzylidene)-propionaldehyde were obtained at 80°-90° C. and0.2 mbar. 35 g of this compound, 100 ml of cyclohexane and 1 g ofhydrogenation catalyst (5% Pd on active carbon) were put into a 0.5 lshaking autoclave. The autoclave was pressurized to 70 bar with hydrogenat 25° C. and shaken at 40° C. for 7 hours. Distillation through arotating band column gave 15 g of2-methyl-3-(3-methylphenyl)-propan-1-ol (boiling point 70° C. at 0.1mbar).

EXAMPLE 2 2-Methyl-3-(3,5-dimethylphenyl)-propan-1-ol

25 g of magnesium turnings and 155 g of 3,5-dimethylbenzyl chloride werereacted in 300 ml of ether. After dilution with 200 ml oftetrahydrofuran, a mixture of 92.5 g of chloroacetone and 100 ml oftetrahydrofuran was added dropwise with ice cooling in the course of onehour. After reacting for 2 hours at 25° C., the mixture was poured ontoa mixture of ice and 2.5 mol hydrochloric acid. The upper layer wasseparated off and the aqueous layer was extracted with ether. Thecombined organic layers were washed with water until neutral, driedusing Na₂ SO₄, filtered and distilled. 110 g of1-chloro-2-(3,5-dimethylbenzyl)-propan-2-ol were obtained at 110°-112°C./0.2 mbar. 109 g of this compound were stirred at 30° C. for 2 hourswith 20 ml of methyl tert.-butyl ether and a solution of 31 g of NaOH in750 ml of water. The layers were then separated, and the organic phasewas washed with water until neutral, dried using Na₂ SO₄ and distilled.65 g of 2-(3,5-dimethylbenzyl)-propylene oxide were obtained at aboiling point of 68°-70° C./0.3 mbar. 80 g of this compound weredissolved in 100 ml of cyclohexane and put into a 0.5 l shakingautoclave with 0.8 g of 5% Pd on active carbon. After flushing withinert gas, the autoclave was pressuried with hydrogen (130 bar) andheated at 150° C. for 8 hours. The cooled mixture was depressurized,flushed with inert gas, the catalyst was filtered off and the filtratewas distilled through a 30-cm long column containing steel helices. 18 gof 2-methyl-3-(3,5-dimethylphenyl)-propan-1-ol passed over at 80°-81°C./0.07 mbar.

EXAMPLE 3 Methyl-3-(3-methylphenyl)-propan-1-ol

500 ml of toluene, 207 g of ground potassium carbonate, 8 g of potassiumiodide, 7 g of 18-crown-6 and 209 g of diethyl methylmalonate wereinitially introduced into a 2 l four-necked flask. The mixture washeated to 85° C. with stirring. 141 g of 3-methylbenzyl chloride wereadded dropwise in the course of half an hour and the mixture was thenstirred at 90° C. for 8 hours. After cooling, the salts were removed byrepeatedly shaking with water and the organic layer was distilled. 184 gof diethyl 2-methyl-2-(3-methylbenzyl)-malonate were obtained at aboiling point of 120° C. and a pressure of about 0.02 mbar. Forhydrolysis, the ester was boiled under reflux with stirring for 16 hourswith 60 g of NaOH, 170 ml of water and a spatula tip-full oftetradecyltrimethylammonium bromide, ethanol which formed in themeantime being distilled off. The dicarboxylic acid was liberated byacidifying with hydrochloric acid, separated off and heated in xylenefor 4 hours under reflux for decarboxylation. The monocarboxylic acidwas then esterified with ethanol (p-toluenesulfonic acid as catalyst,cyclohexane as entraining agent for water). 115 g of ethyl2-(3-methylbenzyl)-propionate (boiling point 70°-73° C. at 0.03 mbar)were obtained. For hydrogenation, 21 g of LiAlH₄ were dissolved orsuspended in 800 ml of tetrahydrofuran in a 2 l four-necked flask undernitrogen. A mixture of 110 g of ethyl 2-(3-methylbenzyl)-propionate and100 ml of tetrahydrofuran were then added dropwise with ice cooling. Themixture was then decomposed with ice and hydrochloric acid, extractedwith ether and dried over K₂ CO₃, and 75 g of2-methyl-3-(3-methylphenyl)propan-1-ol (boiling point 68°-70° C. at 0.1mbar) were obtained by distillation.

Odor Pattern: watery-floral, green-fruity

EXAMPLE 4 2-Methyl-3-(3,5-dimethylphenyl)-propan-1-ol

Example 3 was repeated with 3,5-dimethylbenzyl chloride.2-Methyl-3-(3,5-dimethylphenyl)-propan-1-ol (boiling pint 83° C. at 0.1bar) was obtained.

Odor note: rosy, green

EXAMPLE 5 1-(3-Methylphenyl)-2-methylbutan-3-ol

256 g of methyl ethyl ketone, 80 g of powdered NaOH, 28 g of calciumoxide and 10 g of tetrabutylammonium bromide were warmed with stirring.141 g of 3-methylbenzyl chloride were added dropwise in the course of 90minutes at 70° C. The mixture was then boiled under reflux for 1 hour,cooled, filtered and washed with methyl ethyl ketone, and the filtratewas concentrated and distilled through a 30-cm long column containingsteel helices. 86% pure 3-(3-methylbenzyl)-butanone was obtained at aboiling point of 80° C. at 0.4 mbar in 40% yield.

A solution of 1 mol of 3-(3-methylbenzyl)-butanone (86% pure) in 300 mlof isopropanol was added drop-wise in the course of 5 hours to 100 g ofaluminum triisopropylate heated to boiling with 300 ml of isopropanol,while a mixture of acetone and isopropanol distilled off slowly througha 50-cm long packed column. After reacting for 8 hours, the distillateno longer contained any acetone. The residual isopropanol was thendistilled off and 300 ml of toluene, 300 g of ice and 300 g of conc.hydrochloric acid were added to the residue. The layers were separated,the aqueous phase was extracted with 300 ml of toluene, and the combinedorganic phases were extracted by shaking with a little water,concentrated and distilled through a Vigreux column at 0.2 mbar. Amixture of 1-(3-methylphenyl)-2-methylbutan3-ol isomers was obtained in85% yield from 78°-80° C.

Odor pattern: green-rosy, somewhat ambered with lime blossom and liliesof the valley.

What is claimed is:
 1. A compound selected from the group consisting of2-methyl-3-(3,5-dimethylphenyl)-propan-1-ol,1-(3-methyl-phenyl)-2-methylbutan-3-ol and1-(3,5-dimethylphenyl)-2-methylbutan-3-ol.
 2. A fragrance composition,comprising:a compound selected from the group consisting of2-methyl-3-(3-(3-methylphenyl)-propan-1-ol,2-methyl-3-(3,5-dimethylphenyl)-propan-1-ol,1-(3-methyl-phenyl)-2-methylbutan-3-ol,1-(3,5-dimethylphenyl)-2-methylbutan-3-ol and a combination thereof;and, a carrier substance.